Análisis de balance de masas en la roca de caja con alteración hidrotermal asociada a la mineralización aurífera del distrito Culampajá, Catamarca, Argentina

Abstract

“Mass balance analysis in the hydrothermal alteration wall rock, Culampajá gold Disdrict, Catamarca, Argentina”. In the Altohuasi-Culampajá mountains, (located in Cat- amarca province), which are part of the Sierras Pampeanas Occidentales, gold bearing quartz veins crosscut a deformed granite, of possibly Cambrian-Ordovician age. The most characteristic structural feature of the area is mainly represented by a NNW-SSE trending shear zone. The hydrothermal alteration is dominated by sericitic alteration. Locally K-feldspa- thization is also observed. The mineralogy of the veins is defined by quartz as the main gangue mineral with pyrite, chalcopyrite, native gold, covellite, goethite, hematite, azurite and malachite. Three gold-bearing areas were investigated: Tajo Largo (within the El Moradito group), La Rosario, La Alumbrera and Lomas del Pachao located 10.5 km south of the Quebrada de La Alumbrera. The geochemical mass balance study of the granitic wall rock, using the isocon method, indicate Fe and Ca depletion in all samples, and Mg depletion in same cases. K enrichment was observed in same samples, and Au, Pb, Y, U, Bi, W and Sn are also enriched. Geochemical and petrographic studies, indicate an homogeneous hydrother- mal fluid in the mineralized studied area.